To provide a method by which a seamless tube without a carburized layer on its inside surface is highly efficiently manufactured.
Rough rolling with a mandrel mill using a graphitic lubricant, reheating and finish rolling with a stretch reducer are continuously executed, thereafter, after making thickness of residual oxided scale ≤10μm by executing descaling process on the inside surface of the tube, heat treatment for decarburization in which a tube is heated and kept at 1100-1250°C for 3-20min in an oxidizing atmosphere is executed. In this way, products excellent in inside- surface property, of course, cutting property and corrosion resistance are manufactured at high productivity. And, the occurrence of energy loss is prevented. Further, it is not necessary to provide specialized equipment for descaling the inside surface of tube, so the cost of equipment is reduced.
MASATOMO HIROAKI
ANRAKU TOSHIRO
NAKANISHI TETSUYA
IIDA SUMIO
